[ARM] 5251/1: remove old LED support for Trizeps4 SOM

Remove the old led support in arch/arm/mach-pxa/leds...
for TRIZEPS4 SOM. It is / will be replaced by generic
led driver drivers/leds/...

Signed-off-by: Jürgen Schindele <linux@schindele.name>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>